the purpose of fetching data from PHP into a web page which has already loaded, without reloading the entire page.

More than just ‘intelligent’ forms, if/when this takes off that’ll be the end of hitting submit buttons. chregu continues:

But my master plan is, to replace the whole submit/save/reload circle
with a more "natural" way. So if you click "submit", the page isn’t
send, but just the data in the background. The page has not to be
reloaded and you just can work further on the same document. The same
should go for loading a new record entry, just choose it from an
(automaticly retrieved) pop-down field and the data is loaded from the
network, without having to reload the whole page.